Carburetor



Aug. 16, 1938. J. R. EMERSON '2,127,444

` l cARBUREToR I Filed May 2s, 1934 2 sherets-sheet 1 Aug. `16, 1938. J. R. EMERSON CARBURETOR Filed May 25, '1934 2 Sheets-Sheet 2 Patented Aug. 16, 1938 t 'PATENT' N- OFFICE cAnBUaEToR John n. Emerson, runt, Mich., assigner, by meme assignments, to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Application May 23, 1934, Serial No. 727,035

i 13 Claims.

The invention relates in general to a carburetor for-internal combustion engines and relates 'in particular to down-draft carburetors of the plaintube type. f

An object of the invention is to provide a car fburetor of the character described in whichthe main nomic feed is brought in smoothly as the` engine speed and throttle opening are increased above` idling speed and position respectively.

More particularly itis an object of the invention to provide a carburetor of the down-draft, plain-tube type in which fuel is conducted fromv the emulsion tube to the throttle valve in the form of a film during the initial feed of the` emulsion tube under low suction.

Another object of the invention is to provide in a carburetor a fuel supply nozzle having incorporated therein a 'bubble diffuser for breaking up vapor bubblesiormed i`n the nozzle.

.Yet another object is to provide a fuel supply nozzle of noyel and improved construction having an air-swept tip causing the nozzle to discharge at unusually low suction.

Other objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings, in which j f Figure 1 is a vertical sectional view through A one carbureting passage of aV duplex carburetor embodying the features of the invention.

Figure 2 is a fragmentary view taken along' line 2--2 oi Fig. 4-1 and showing in elevation a preferred form of fuel conducting means. e

Figure 3 is a view showing a modified form of `fuel conducting means.

Flure 4 shows still another form ducting means.. l

Figure 5 shows yet another form of fuel conducting means.

I While the. invention is shown in the drawings and will be described herelnafter'as embodied in of fuel cona carburetor of the down-draft type, it is not intended thereby to limit the invention to the 4 specific construction shown but it is intendedi to cover all modifications `and alternative construc- "tions fallingv within the spirit and scope o f the invention as de ned by the appended claims.

The carburetor shown by way-ofillustrationin the drawings comprises a body member generally designated providing an airjlntake passage 6, having a downwardly directed venturi 1 therein, and a fuel bowl il. Secured to the top of the body member Ii is a 'cover member 9 providing a closure Il for the top of the fuel bowl and an extension passage l' for the intake passage i. A

'Patent No. 2,050,995 of Aug. 11,

buttery choke valve II controls the airintake passage Ii'. Bolted -to the bottomof the body member 5 is a throttle body I2 providing a combustible mixture discharge passage I3 which is 'controlled by a buttery throttle valve I4 mounted l on a throttle shaft I5 extending transversely of the passage. Disposed centrally of the passage 6 andterminating in the venturi 1 is 'an emulsion tube I6 receiving an emulsion of' air and fuel discharged from a main nozzle generally designated I1. The tube I6 is preferably cast as an integral part of. the body member 5. w

In carburetors of the plain-tube type, the suction on the main nozzle is not sfiicient to cause a discharge of fuel therefrom when the throttle is substantially closed, as shown in Fig. 1, to re duce the engine to idling speed. Under 'such conditions ,fuel is supplied tothe engine by means of an idling fuel supply system as is .well known in the art. (Such ya system is shown in jet I9 is controlled by an adjusting needle 20 193eV and carrying a serrated head 2l' for convenient ad- .iustmenu4 A secondary idle air vent 22 communicates with the passage I3\ above the throttle valve to supply additional air to the emulsion in the channel I8 as well as does an idle control opening 23 communicating with the passage I3 vjust above the throttle I4 when in idling position. The idle control opening 23 also functions as a fuel discharge means when the throttle valve is opened slightly beyond idle position to aid theidle fuel jet in supplying'suiilcient fuel. g

As the throttle is opened to increase the engine speed or to provide additional fuel for climbing or accelerating, the suction on the idling fuel supply;

system gradually decreases and the suction on' the main nozzle I1 increases so that the function of supplying fuel is gradually transferred from the idling system .to the main nozzle. Herein thenozzle is located in a bore 24 in the body memy ber 5 and .comprises a tubular member 25 shorter -than the bore and having a ductl 26 extending therethrough. The nozzle terminates in a'cap 21 extending into the emulsion tube I6. and having a' sleeve portion 21 abutting a. shoulder 25' on the end of the tubular member 25 and a screw cap 2l closing the lower end of the bore 24 retains the nozzle in the upper end oflthe bore.

Fuel is supplied to the nozzle from the fuel bowl l through a channel 30 communicating with the bore 24 at the space between the lower end of the tubular member 25 and the screw cap 2s and alsothrough a bowl feed Jet Il communicating with an annular groove 22 formed in the member 2l and in turn communicating with the duct 2l therein by means of radial passages I3. An air vent jet draws air from the intake passage I and discharges the same intoan air vent annulus l5 formed in the member 2l Just below the upper end thereof. The air so discharged flows past the end of the tubular member 2l and draws fuel from the duct 2| to form an emulsion of fuel and air subsequently discharged from the nomic cap 21.

In order to prevent vapor bubbles from forming in the duct 2t of the nozzle l1 and carrying with them the fuel in the .duct as they rise to the top of the nozzle, means is provided to diffuse the bubbles so formed and break them up into bubbles which are small enough to pass up the bore. to lbe dissipated at the top of the nozzle, without carrying fuel with them. This means comprises simply a fine wire It extending centrally of the duct 26. The wire is fast at its lower end with a flanged collar 'receivedin a recess 2l' in the screw cap and retained therein by the spring 2l bearing against the flange on the collar.

As above stated, when the throttle is opened to increase the engine speed or to load theengine at any speed, the suction on the manifold 'side of the throttle is decreasedand vthe fuel feed is ac- ..cordingly transferred from the idling fuel supply system to the main nozzle I1. Because of the high velocity at which air passes from the nozzle air vent annulus Il past the end of the tubular member 25, feed from the nozzle starts at very l low suction at the nozzle and before the quantity of air passing through the emulsion tubev Il is sumcient to break up the fuel into small drops. 'Ihe feed from the nozzle I1 at low suction is. therefore, in the form of large intermittent'drops. This manner of feed is inherent in plain-tube, emulsion-feed carburetors and is particularly undesirable in carburetors of the down-draft type because the large, intermittent drops fall from the emulsion tube onto the throttle valve Il where they are broken up and immediately drawn into the manifold therebysupplying a mixture which is intermittently materially richened and thus produces a rolling. irregular operation ,of the. motor. It has long been a problem, therefore, to bring in the feed of the main noaale smoothly and without the irregular motor operation described.

Means is'provided herein for bringing in the feed of the main nozzle smoothly. The means operates by conducting the initial, intermittent discharge from the emulsion tube in the form of a nlm from the tube to the throttle valve from' which it is sucked oi! at a more uniform rate.

, The means may take a variety of forms and may be compod of any material capable of conducting fuel from the emulsion tube to the throttle valve in the form of a nlm as contrasted with drops. A preferred form is shown'herein simply as a generally U-shaped member I1 (see Hg. 3) bentfromwire. Thememberissecuredtothe emulsiontube Ilbymeansofcoiisllformedby theends ofthewirecomposingtbememberand encircling the emulsion tube. The wires dovnwardiyalongdiametricallyoppossd i of the tube il and at the' discharge end of the tube engage in longitudinal grooves, formed by pairs of lugs Il, to secure the member in position. Immediately below the tube Il the wires are formed withoifsets Il which bring the wires inwardly beyond the inner circumference of Ithe tube. The member 31 extends downwardly to a point adjacent the throttle valve Il and in fact preferably contacts the throttle shaft i5 to facilitate the transfer of the fuel from the member to the throttle shaft.

By the use of the member l1 the initial operation of the main nozzle I1 is brought in smoothly and without the' customary irregular operation of the engine. At low suction when the discharge from the main nozzle is in the form of large, in

termittent drops, substantially all the fuel is conducted down the member 21 in the form of a film and is then sucked from the throttle valve at a comparatively uniform rate. As the throttle opening is increased so that the flow of air through the emulsion tube it is at a velocity to cause the drops to be broken up into fine particles, less fuel is conducted down the member 31. However, at such increased'throttle opening the feed from the nozzle i1 is no longer intermittent but substantially uniform and the energy of the air nowing within the emulsion tube is sufficient to break the fuel into fine particlesso that a mixture of substantially uniform richness is supplied to the manifold. l

Modined forms of the conducting member I1 v are shownin Flgs. 3 to 5. In Fig. 3 the member comprises a plurality of wires 4I, there being shown herein, the upper ends of which are received in circumferentially spaced grooves 42 formed on the discharge end of the emulsion tube It. The wires 4l arebent sharply inwardly below the emulsion tube II and turned to form a twisted portion I3 which extends downwardly into contact with theI throttle shaft i5. With the basket-like construction formed by the inwardly bent wires, the member is effective to catch the drops of fuel which pass centrally throuh the emulsion tube as well as the fuel that accumulates on' the lower edge thereof. The construction, however, is open so as not to interfere with the discharge from the tube when the energy is sufiicient to particles.

In l'lg. 4 the conducting member takes the form of a single wire M secured at its upper end in the noasleeap 21 and projecting downwardly through the discharge. opening 21" therein and axially of'l the emulsion tube into contact with the throttle shaft Il. In Pig. 5 the conducting member takes the form of a tapered strip or ribbon el disposed diametrically ofthe emulsion tube Il and extending downwardly into contact with the throttle valve shaft il. The ribbon 4I is conveniently attached to the tube by securing the Same in slots 4I formed in the tube. In each of the forms the conducting member does not interfere with the discharge from the nozzle under high energy but does .conduct the intermittent low energy o r low suction discharge in the formV break4 the fuel into small' ventun-tbereimatubularmsmberextendingax- 'I6 ially of and discharging into said venturi; a main fuel supply nozzle discharging into saidvtubular member, a throttle valve controlling the flow of combustible mixture from the carburetor, said main nozzle being inoperative when said throttle valve is substantially closed foridling the engine, an idling fuel supply system having a Jet discharging into the carburetorata point beyond the throttle valve to supply fuel to the engine when the throttle is substantially closed for idling the engine, and means for conducting the discharge from the main nozzle to the throttle valve when the main nozzle is functioning under low suction.

2. In a plain-tube, down-draft carburetor, av

body member providing an air intake passage having a venturi, main fuel supplyy means including anemulsion tube discharging into the venturi and a nozzle discharging into the emulsion tube, a throttle valve controlling the flow of cornbustible mixture from the carburetor, said main fuel supply being inoperative when said throttle valve is substantially closed for idling the engine, an idling fuel supply system having a jet discharging into the'carburetor at`a point beyond the throttle valve, and means engaging the main fuel supply means and extending downwardly into engagement-with the throttle valve to conduct.

fuel in the form of a fllm from said main supply means to said throttle valve when said main supply is operating at low suction.

3. In a down-draft carburetor for an internal combustion engine, a body member providing an air intake passage having a venturi, a float bowl, `an emulsion tube disposed longitudinally of and discharging into said venturi, an air bleed main fuel supply nozzle discharging into said emulsion tube fuel drawn by suction from said float bowl, a throttle valve controlling the flow of combustible mixture from the carburetor to the engine. a fuel supply system having a jet discharging into the carburetor at a point beyond the throttle valve to supply fuel for idling speeds of the engine, and means engaging the emulsion tube at its discharge end and extending downwardly to a point adjacent said `throttle valve to conduct fuel in the form of a film from said emulsion tube to said throttle valve when said main nozzle is operating at low suction.

4. In a down-draft carburetor, a body member providing an air intake passage having a venturi, an emulsion tube discharging into the venturi, a main fuel nozzle discharging an emulsion of fuel and airinto said emulsion tube, a throttle valve controlling the discharge from said nozzle by controlling the flow of'air through the intake passage, and means engaging said emulsion tube at its discharge end and extending downwardly into contact with said throttle valve for conducting fuel from 'said emulsion tube to said throttle v'alve in the form of a film to bring in smoothly the operation of said main nozzle.

5. In a plain-tube, down-draft carburetor for an internal combustion engine-a body member providing an air "intake passage having a venturi, an emulsion tube discharging into the venturi, a main fuel nozzle discharging' in'to said emulsion tube, a. throttle valve for controlling the `aupply of combustible mixture from the carburetor to the engine, and meansv for bringing in smoothly the operation of said main supply nozzle comprising a vU-shaped wire member secured to said emulsion tube in contact with the discharge end'thereof and extending downwardly into contact with said throttle valve.

6. In a plain-tube, ldown-draft-carburetor, a

- body member providing an air intake passage 4its lower end pairs of lugs forming longitudinal 5 grooves disposed diametrically opposite each other, a main fuel supply nozzle discharging into said emulsion tube, a throttle valve for controlling the supply of combustible mixture from the carburetor, a throttle shaft supporting said throttle valve and means for bringing in smoothly the operation of said main supply nozzle comprising a U-shaped wire member bent at its free ends to form coils encircling said emulsion tube and extending downwardly into contact with said throttle shaft, said member engaging in the grooves formed in the emulsion tube and being offset inwardly immediately below the tube.

7. -In a plain-tube, down-draft carburetor, a body member providing an -air intake passage having a venturi, an emulsion tube discharging into the venturi, a main fuel supply nozzle discharging into said emulsion tube, a throttle valve for controlling the flow ofcombustible mixture from the carburetor, and a single wire projecting from the nozzle through the discharge opening therein and extending downwardly centrally of the emulsion tube into contact with said throttle valve.

8. In aplain-tube, down-draft carburetor, a body member providing an air intake passage having a venturi, an emulsion tube discharging into the venturi, a main fuel supply discharging into said emulsion tube, a throttle valve for controlling the flow of combustible mixture from the carburetor, and a at ribbon disposed diametrically of said emulsion tube and extending downwardly yinto contact with said throttle valve to conduct fuel, in the form of a nlm from the emulsion tube-during operation of the main nozzle at low energy. 9. In a carburetor a main body member providing a carbureting passage and a fuell bowl, an emulsion tube integral with said body member disposed longitudinally of the passage and opming to the passage at both ends, an inwardly andv upwardly extending bore in said body'member communicating at its lower end with the fuel bowl and terminating at the other end in said emulsion tube, a nozzle cap in the bore projecting outwardly thereof into the emulsion tube and discharging in the direction ofair flow through the tube, a tubular member in the bore spaced from the cap to provide therewith a discontinuous duct leading from the fuel bowl to the emulsion tube, said member being formed with an air vent annulus at the end adjacent the cap, and an air vent jet discharging into the annulus.

10. In a down-draft carburetor a main body member providing a carbureting passage and fuelbowl, a downwardly discharging emulsion tube disposed longitudinally of the passage, a bore leading from the fuel bowl tothe upper end of said emulsion tube, means forming a shielded opening from said bore into the emulsion tube discharging in the direction of fiow therethrough, a tubular member fitting snugly within the bore and terminating .in a reduced end spaced from the end of the bore. said member having a duet therethrough, and an air,L vent let opening up wardly in the passage and discharging into the bore opposite the reduced end of the tubular member whereby the air sweeping past the end of the member draws fuel from the duct.

1'1. In a down-draft Acarburetor a main body l5 member providing a carbureting passage and a` fuel bowl, an emulsion tube disposed longitudinally of -the passage, 'a bore leading upwardly from the fuel bowl to the emulsion tube, a nozzle cap with a passage therethrough fitting snugly in the upper end of the bore and projecting outwardly thereof into said emulsion tube, a tubular member having a duct extending longitudinally therethrough fitting snugly within the lower porv tion of the bore and terminating short of the passage in the cap to provide a discontinuous duet leading from the fuel bowl to the emulsion tube, an air vent annulus formed about the end of the member adjacent the cap, an air vent jet opening upwardly into thepassage and discharging into the annulus to draw fuel from the duct as the air sweeps past the end of the member,

- discharge of said nozzle in the form of tle valve controlling the flow of 4combustible mixture from the carburetor, said main nozzle being inoperative when said throttle valve is substantially closed for idling the engine, an idling fuel supply system having a jet discharging into the carburetor at a point beyond the throttle valve to supply fuel to the engine ,when the throttle is substantially closed forl idling the engine, and means depending from thewdischarge end of 'said tubular member for arresting drop discharge therefrom when the main nozzle is functioning under low suction and bringing in smoothly the operation of the main nozzle.

13. In a down-draft carburetor, a body member providing an air intake passage, a tubular member extending longitudinally of the passage and discharging thereinto, a main fuel nozzle discharging into said tubular member, a throttle valve located posterior to said nozzle controlling the discharge therefrom by controlling the flow of air through the intake passage, and means engaging said tubular member at its discharge end and extending downwardly into contact with said throttle valve for conducting the low suction a nlm to the high suction edge of said throttle valve.

- JOHN' R. EMERSON. 

